It is common to recover for reuse or recycling scrap iron or steel from discarded products, such as automobiles or the like. One particular type of recycling which presents special waste disposal problems is the recovery of scrap iron or steel from automotive engines and transmissions which are bathed in oil. The clean, sorted cast iron produced in such a recovery process is typically sold as scrap iron feed for subsequent industrial and foundry use.
In a typical recovery process, automotive scrap engines and transmissions are dropped into a large hopper in which a hydraulic ram breaker machine crushes them into fragments having widths of approximately 2 to 6 inches. This crushed, fragmented material is then passed onto a conveyer belt in which the nonmetallic components, such as wire, hoses and the like are removed from the metal scrap stream. These crushed fragments are then passed into a rotary drum washer in which the fragments are tumbled and washed by a heated detergent and water solution. The water typically is heated for the washing cycle by a separately powered water heater which circulates heated water to the washer in a continuous cycle. The resulting clean cast iron is then discharged from the washer to another conveyer belt which conveys the fragments to a sorting building. In the sorting building, the crushed material is separated into cast iron and steel. The material is then transported out of the sorting building into exterior storage piles, after whch it is shipped by rail or truck to foundry customers.
During washing of the fragments in the washer, heavy sludge containing small cast iron grit settles out of the continuous flow of hot detergent water and into the bottom of the tank. The waste water also contains oily wastes which are permitted to settle out. Both this oily waste and the washer sludge in most typical prior art systems are removed and hauled away to a local landfill dump for disposal.
This disposal of the heavy sludge and oily wastes resulting from this recovery process has presented certain health problems because of the toxic nature of the waste product, which often includes lead and many ferrous compounds. These materials tend to leach into the soil and often reach the water supply system near the landfill disposal site. As a result, landfill disposal of such sludge and oily waste is no longer permitted in many areas, thus presenting a problem for operators of such scrap recovery systems and substantially increasing the cost thereof. Prior to this invention, no fully acceptable commercially used alternative existed for the disposal of this heavy sludge. In addition, no fully acceptable commercially used system was available for recovery of the waste products contained in this heavy sludge or oily waste.